Generalize the RotatingLogger; size, time or first of the two trigger the rollover

[j-c-cook]

A RotatingLogger object is created that constrains the file by file size, time or both. In the case of when both are constrained, the first that occurs will trigger the rollover.

• Adds a deprecation warning to the TimedRotatingLogger. The TimedRotatingLogger now inherits from the generalized RotatingLogger.
• When time is a constraint for the RotatingLogger, don't rollover if there have been no messages received since the last rollover
• Update the doc string under RotatingLogger
• Fix the tests to make them run with these changes

closes #1364

[j-c-cook]

The BLFWriter will be able to be used like the following:

python -m can.logger -i socketcan -c vcan0 -b 250000 -f file.blf -t 600 --compression-level=1 --max-container-size=200000

Here, a rollover would occur every 5 seconds, or when the buffer and file size becomes 200000. Note that the default max_container_size is 128 * 1024.

Another option would be:

python -m can.logger -i socketcan -c vcan0 -b 250000 -f file.log -t 600 -s 100000

A rollover would occur every 5 seconds, or when the file size becomes 100000 bytes.

[j-c-cook]

• When time is a constraint for the RotatingLogger, don't rollover if there have been no messages received since the last rollover

This is inherent to the implementation of logger. When a message is received then the logger is called. The file cannot rollover without there being a message passed to logger.

python-can/can/logger.py

Lines 246 to 251 in 88fc8e5

	try:
	while True:
	msg = bus.recv(1)
	if msg is not None:
	logger(msg)
	except KeyboardInterrupt:

[codecov]

Codecov Report

Merging #1365 (22bf537) into develop (4b1acde) will increase coverage by 0.12%.
The diff coverage is 100.00%.

❗ Current head 22bf537 differs from pull request most recent head cabafb4. Consider uploading reports for the commit cabafb4 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1365      +/-   ##
===========================================
+ Coverage    65.16%   65.29%   +0.12%     
===========================================
  Files           81       81              
  Lines         8853     8779      -74     
===========================================
- Hits          5769     5732      -37     
+ Misses        3084     3047      -37     

[j-c-cook]

@zariiii9003 This RotatingLogger class has been successfully running on multiple devices, that I manage, for about a month now (prior to the refactoring I've done today). There have been tens and possibly hundreds of hours of testing on the class by now. It is ready for a review. Please let me know what you think, thanks.

[felixdivo]

Regarding the discussion in #1364: I generally think that separating what can be split is a fair goal. In this case, however, I think having one class for this makes a lot of sense since it does simplify both user code and the implementation (I think having cooperating sub-classes to have a logger that supports both variants of rotations will not be easier to understand than this).

There are also a few nice small improvements in here that should be merged regardless of the new features!

We should finish the talk about the general API in #1364 before merging here.